Cyclic phenomena in the circumstellar gaseous envelope of the candidate Herbig A0e star HD 163296^*

¹ Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, 196140 Saint-Petersburg, Russia e-mail: beskr@pulkovo.spb.su
² Departamento de Física - ICEX - UFMG, Caixa Postal 702, 30.161-970 - Belo Horizonte - MG, Brazil
³ Department of Physics - Keele University, Keele, Staffordshire ST5 5BG, UK

Send offprint request to: N.G. Beskrovnaya

Received: 26 February 1997
Accepted: 13 May 1997

Abstract

We present new results of a spectroscopic and polarimetric investigation of the candidate young Herbig Ae/Be star HD 163296. Twenty two spectra of this object near the , He i 5876  and DNa i lines had been obtained in 1992–1995 at the Astrophysical National Laboratory of Brazil (LNA). In addition, forty seven high-resolution spectra in Hα and Hβ were obtained at the ESO (Chile) in 1991–1992. -polarimetry (about forty measurements of the Stokes parameters in each passband) were carried out at the SAAO (South Africa) in July 17–30, 1995.
Striking profile variability has been found in all the lines on time scales from hours to months. Analysis of the profiles revealed manifestations of a remote cool shell which is in active interaction with the variable kinematically stratified stellar wind. Signs of cyclic positional variations of the Hα and Hβ emission peaks were observed during five nights in July, 1991.
Sinusoidal variations of the linear polarization parameters detected in July, 1995 are explained in the framework of a model involving magnetized gaseous condensation, rotating in the envelope with the period of 15 days.
Marginal detection of circular polarization is also reported.